Till Rohrmann created FLINK-10052:
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Summary: Tolerate temporarily suspended ZooKeeper connections
Key: FLINK-10052
URL: https://issues.apache.org/jira/browse/FLINK-10052
Project: Flink
Issue Type: Improvement
Components: Distributed Coordination
Affects Versions: 1.5.2, 1.4.2, 1.6.0
Reporter: Till Rohrmann
This issue results from FLINK-10011 which uncovered a problem with Flink's HA
recovery and proposed the following solution to harden Flink:
The {{ZooKeeperLeaderElectionService}} uses the {{LeaderLatch}} Curator recipe
for leader election. The leader latch revokes leadership in case of a suspended
ZooKeeper connection. This can be premature in case that the system can
reconnect to ZooKeeper before its session expires. The effect of the lost
leadership is that all jobs will be canceled and directly restarted after
regaining the leadership.
Instead of directly revoking the leadership upon a SUSPENDED ZooKeeper
connection, it would be better to wait until the ZooKeeper connection is LOST.
That way we would allow the system to reconnect and not lose the leadership.
This could be achievable by using Curator's {{LeaderSelector}} instead of the
{{LeaderLatch}}.
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